Method of handling HARQ resource in TDD system and related communication device

ABSTRACT

A method of determining HARQ resource of a UL subframe comprises determining a first new association set of the UL subframe according to an association set of the UL subframe of a first UL/DL configuration of a legacy communication device; replacing a subset of the first new association set by a subset of an association set of the UL subframe of a second UL/DL configuration of an advanced communication device, when the legacy communication device is not able to perform a reception in at least one subframe corresponding to the subset of the first new association set; configuring a mapping between at least one sequence index of the UL subframe of the first UL/DL configuration and the first new association set according to the first UL/DL configuration; and determining the HARQ resource of the UL subframe according to the mapping and the first new association set.

CROSS REFERENCE TO RELATED APPLICATIONS

This application claims the benefit of U.S. Provisional Application No.61/656,493, filed on Jun. 6, 2012 and entitled “Methods for AssigningHARQ resource in TDD system and apparatus using the same”, the contentsof which are incorporated herein in their entirety.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a method used in a wirelesscommunication system and related communication device, and moreparticularly, to a method of handling hybrid automatic repeat request(HARQ) resource in a time-division duplexing (TDD) and relatedcommunication device.

2. Description of the Prior Art

A long-term evolution (LTE) system supporting the 3rd GenerationPartnership Project (3GPP) Rel-8 standard and/or the 3GPP Rel-9 standardare developed by the 3GPP as a successor of a universal mobiletelecommunications system (UMTS), for further enhancing performance ofthe UMTS to satisfy increasing needs of users. The LTE system includes anew radio interface and a new radio network architecture that provides ahigh data rate, low latency, packet optimization, and improved systemcapacity and coverage. In the LTE system, a radio access network knownas an evolved universal terrestrial radio access network (E-UTRAN)includes multiple evolved Node-Bs (eNBs) for communicating with multipleuser equipments (UEs), and communicating with a core network including amobility management entity (MME), a serving gateway, etc., forNon-Access Stratum (NAS) control.

A LTE-advanced (LTE-A) system, as its name implies, is an evolution ofthe LTE system. The LTE-A system targets faster switching between powerstates, improves performance at the coverage edge of an eNB, andincludes advanced techniques, such as carrier aggregation (CA),coordinated multipoint transmission/reception (CoMP), UL multiple-inputmultiple-output (MIMO), etc. For a UE and an eNB to communicate witheach other in the LTE-A system, the UE and the eNB must supportstandards developed for the LTE-A system, such as the 3GPP Rel-10standard or later versions.

Different from the LTE/LTE-A system with frequency-division duplexing(FDD), directions of subframes of a frequency band in the LTE/LTE-Asystem with time-division duplexing (TDD) may be different. That is, thesubframes in the same frequency band are divided into uplink (UL)subframes, downlink (DL) subframes and special subframes according tothe UL/DL configuration specified in the 3GPP standard.

Please refer to FIG. 1 which is a table 10 of the UL/DL configurationwith subframes and corresponding directions. In FIG. 1, 7 UL/DLconfigurations are shown, wherein each of the UL/DL configurationsindicates a set of directions for 10 subframes, respectively. In detail,“U” means that the subframe is a UL subframe where UL data istransmitted, and “D” means that the subframe is a DL subframe where DLdata is transmitted. “S” means that the subframe is a special subframewhere control information and maybe data (according to the specialsubframe configuration) is transmitted, and the special subframe canalso be seen as the DL subframe in the present invention.

Furthermore, a UL/DL configuration of a legacy UE can be changedaccording to system information (e.g., System Information Block Type 1(SIB1)) transmitted by an eNB, e.g., from the UL/DL configuration 1 tothe UL/DL configuration 3. A minimum periodicity of transmitting theSIB1 is usually large (e.g., 640 ms), and the legacy UE can only changethe UL/DL configuration with the periodicity equal or greater than 640ms. The semi-statics allocation cannot match fast varying trafficcharacteristics and environments, and there is space for improvingsystem performance. Thus, changing the UL/DL configuration with a lowerperiodicity (e.g., lower than 640 ms) is considered.

In general, the legacy UE is configured with a UL/DL configurationaccording to the SIB1, and this UL/DL configuration is also known by anadvanced UE which is configured with an additional UL/DL configuration.The additional configuration is a real configuration operated by theeNB, and the eNB provides services (i.e., performs transmissions and/orreceptions) to both the legacy UE and the advanced UE according to theadditional configuration.

However, when the legacy UE and the advanced UE are configured withdifference UL/DL configurations, a collision of HARQ resources may occurif the legacy UE and the advanced UE intend to transmit HARQ feedbacksin a same UL subframe. The collision may occur due to that the legacy UEand the advanced UE transmitting the HARQ feedbacks by using overlappedHARQ resource (e.g., the same HARQ resource) in the UL subframe. In thissituation, the network cannot detect the HARQ feedbacks transmitted bythe legacy UE and the advanced UE. Communications between the networkand the legacy UE and the advanced UE cannot proceed regularly.

Thus, how to solve the collision of the HARQ resources caused due todifferent UL/DL configurations of the legacy UE and the advanced UE isan important topic to be discussed.

SUMMARY OF THE INVENTION

The present invention therefore provides a method and relatedcommunication device for handling HARQ resource in a time-divisionduplexing (TDD) system to solve the abovementioned problem.

A method of determining hybrid automatic repeat request (HARQ) resourceof an uplink (UL) subframe for an advanced communication devicecomprises determining a first new association set of the UL subframeaccording to an association set of the UL subframe of a firstUL/downlink (DL) configuration of a legacy communication device;replacing a subset of the first new association set by a subset of anassociation set of the UL subframe of a second UL/DL configuration ofthe advanced communication device, when the legacy communication deviceis not able to perform a reception in at least one subframecorresponding to the subset of the first new association set;configuring a mapping between at least one sequence index of the ULsubframe of the first UL/DL configuration and the first new associationset according to the first UL/DL configuration; and determining the HARQresource of the UL subframe according to the mapping and the first newassociation set.

These and other objectives of the present invention will no doubt becomeobvious to those of ordinary skill in the art after reading thefollowing detailed description of the preferred embodiment that isillustrated in the various figures and drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a table 10 of the UL/DL configuration with subframes andcorresponding directions.

FIG. 2 is a schematic diagram of a wireless communication systemaccording to an example of the present invention.

FIG. 3 is a schematic diagram of a communication device according to anexample of the present invention.

FIG. 4 is a flowchart of a process according to an example of thepresent invention.

FIGS. 5-10 are schematic diagrams of association sets of the advanced UEand the legacy UE with different UL/DL configurations according to anexample of the present invention.

DETAILED DESCRIPTION

Please refer to FIG. 2, which is a schematic diagram of a wirelesscommunication system 20 according to an example of the presentinvention. The wireless communication system 20 is briefly composed of anetwork, advanced user equipments (UEs) and a legacy UE. The wirelesscommunication system 20 supports a time-division duplexing (TDD) mode.That is, the network and the UEs can communicate with each other byusing uplink (UL) subframes and downlink (DL) subframes according to oneor more UL/DL configurations. A minimum periodicity for changing anUL/DL configuration of the advanced UE is smaller than a minimumperiodicity for changing a UL/DL configuration of the legacy UE. Thatis, the advanced UE can change its UL/DL configuration fast according tofast varying traffic characteristics and environments. Besides, theadvanced UE know the UL/DL configuration of the legacy UE, e.g.,according to System Information Block Type 1 (SIB1) transmitted by thenetwork. For example, the advanced UE may refer to a communicationdevice supporting the 3rd Generation Partnership Project (3GPP) Rel-11standard or later versions. However, this is not a restriction, and thelegacy UE may also have functions similar to those supported by theadvanced UE via an update, and is not limited herein. In anotherexample, the advanced UE may refer to a communication device support anenhanced interference mitigation and traffic adaption (EIMTA) function.In this situation, the legacy may refer to a communication device whichdoes not enable (e.g., support) the EIMTA function.

In FIG. 2, the network and the UEs are simply utilized for illustratingthe structure of the wireless communication system 20. Practically, thenetwork can be a universal terrestrial radio access network (UTRAN)comprising a plurality of Node-Bs (NBs) in a universal mobiletelecommunications system (UMTS). Alternatively, the network can be anevolved UTRAN (E-UTRAN) comprising a plurality of evolved NBs (eNBs)and/or relays in a long term evolution (LTE) system, a LTE-Advanced(LTE-A) system or an evolution of the LTE-A system.

Furthermore, the network can also include both the UTRAN/E-UTRAN and acore network, wherein the core network includes network entities such asMobility Management Entity (MME), Serving Gateway (S-GW), Packet DataNetwork (PDN) Gateway (P-GW), Self-Organizing Networks (SON) serverand/or Radio Network Controller (RNC), etc. In other words, after thenetwork receives information transmitted by a UE (advanced UE or legacyUE), the information may be processed only by the UTRAN/E-UTRAN anddecisions corresponding to the information are made at theUTRAN/E-UTRAN. Alternatively, the UTRAN/E-UTRAN may forward theinformation to the core network, and the decisions corresponding to theinformation are made at the core network after the core networkprocesses the information. Besides, the information can be processed byboth the UTRAN/E-UTRAN and the core network, and the decisions are madeafter coordination and/or cooperation are performed by the UTRAN/E-UTRANand the core network. A UE can be a mobile phone, a laptop, a tabletcomputer, an electronic book or a portable computer system but is notlimited. Besides, the network and the UE can be seen as a transmitter ora receiver according to direction, e.g., for an UL, the UE is thetransmitter and the network is the receiver, and for a DL, the networkis the transmitter and the UE is the receiver. More specifically, forthe network, the direction of the transmission is DL, and the directionof the reception is UL. For the UE, the direction of the transmission isUL, and the direction of the reception is DL.

Please refer to FIG. 3, which is a schematic diagram of a communicationdevice 30 according to an example of the present invention. Thecommunication device 30 can be an advanced UE, the legacy UE or thenetwork shown in FIG. 2, but is not limited herein. The communicationdevice 30 may include a processing means 300 such as a microprocessor orApplication Specific Integrated Circuit (ASIC), a storage unit 310 and acommunication interfacing unit 320. The storage unit 310 may be any datastorage device that can store a program code 314, accessed and executedby the processing means 300. Examples of the storage unit 310 includebut are not limited to a subscriber identity module (SIM), read-onlymemory (ROM), flash memory, random-access memory (RAM), CD-ROM/DVD-ROM,magnetic tape, hard disk and optical data storage device. Thecommunication interfacing unit 320 is preferably a transceiver and isused to transmit and receive signals (e.g., messages or packets)according to processing results of the processing means 300.

Please refer to FIG. 4, which is a flowchart of a process 40 accordingto an example of the present invention. The process 40 is utilized inthe advanced UE shown in FIG. 2, for determining hybrid automatic repeatrequest (HARQ) resource of a UL subframe. The process 40 may be compiledinto the program code 314 and includes the following steps:

Step 400: Start.

Step 402: Determine a first new association set of the UL subframeaccording to an association set of the UL subframe of a first UL/DLconfiguration of the legacy UE.

Step 404: Replace a subset of the first new association set by a subsetof an association set of the UL subframe of a second UL/DL configurationof the advanced UE, when the legacy UE is not able to perform areception in at least one subframe corresponding to the subset of thefirst new association set.

Step 406: Configure a mapping between at least one sequence index of theUL subframe of the first UL/DL configuration and the first newassociation set according to the first UL/DL configuration.

Step 408: Determine the HARQ resource of the UL subframe according tothe mapping and the first new association set.

Step 410: End.

According to the process 40, the advanced UE first determines a firstnew association set of the UL subframe according to an association setof the UL subframe of a first UL/DL configuration of the legacy UE.Then, the advanced UE replaces a subset of the first new association setby a subset of an association set of the UL subframe of a second UL/DLconfiguration of the advanced UE, when the legacy UE is not able toperform a reception in at least one subframe corresponding to the subsetof the first new association set. Then, the advanced UE configures(e.g., establishes) a mapping between at least one sequence index of theUL subframe of the first UL/DL configuration and the first newassociation set according to the first UL/DL configuration (i.e., themapping of the UL subframe of the first UL/DL configuration), anddetermines the HARQ resource of the UL subframe according to the mappingand the first new association set. In other words, the advanced UEdetermines the HARQ resource for transmitting HARQ feedbacks accordingto the UL/DL configuration of the legacy UE and properties (e.g.,directions) of subframes to be acknowledged. Note that the subset may bethe entire set. For example, the entire first new association set isreplaced. In another example, the subset of the first new associationset may be replaced by the entire association set of the UL subframe ofthe second UL/DL configuration. Thus, the collision of the HARQresources can be solved, while the operation of the legacy UE is notaffected. As a result, communications between the network and the legacyUE and the advanced UE can proceed regularly.

Please note that, realization of the process 40 is not limited. Pleaserefer to FIG. 5, which is a schematic diagram of association sets of theadvanced UE and the legacy UE with different UL/DL configurationsaccording to an example of the present invention, wherein subframeallocations corresponding to the UL/DL configurations are shown in theupper half of FIG. 5. In detail, the advanced UE and the legacy UE areconfigured with the UL/DL configurations 3 and 4, respectively, whereinthe UL/DL configuration of the legacy UE may be a SIB1 configuration.Association sets for various UL subframes and UL/DL configurations areshown in FIG. 5. For example, the association set of the subframe 2which includes the association set indices 7, 6 and 11 will be used fordetermining HARQ resource according to the prior art, when the advancedUE intends to transmit a HARQ feedback in the subframe 2. In addition,the HARQ feedback corresponds to DL receptions in DL subframescorresponding to the association set indices 7, 6 and 11, wherein the DLsubframes are the subframes 5, 6 and 1 of a previous frame in thepresent example. The sequence indices m mapping to the association setindices are shown on the top of the association set. For example, theassociation set indices 7, 6 and 11 of the subframe 2 of the UL/DLconfiguration 2 are mapped by the sequence indices 0, 1 and 2,respectively.

According to the process 40 and the above description, the advanced UEcan determine the first new association set as the association set ofthe legacy UE, replace the subset of the first new association set bythe subset of the association set of the UL subframe of the UL/DLconfiguration 3 when the legacy UE is not able to perform the receptionin the at least one subframe corresponding to the subset of the firstnew association set, and configure the mapping between the sequenceindices and the first new association set as the mapping used by thelegacy UE. Preferably, each association set index of the subset of theUL subframe of the UL/DL configuration 3 and each association set indexof the rest of the first new association set (i.e., association setindex not being replaced) are different. That is, when the subframe 2 isconsidered, the advanced UE first determines the first new associationset as (12, 8, 7, 11). Then, the advanced UE replaces the associationset index 8 by the association set index 6, since the association setindex 8 corresponds to the subframe 4 in the previous frame and thesubframe 4 is actually a UL subframe. More specifically, the subframe 4is a DL subframe determined according to the UL/DL configuration 4operated by the legacy UE, and is the UL subframe determined accordingto the UL/DL configuration 3 which is the real configuration operated bythe network and the advanced UE. The association set indices 7, 6 and 11are now mapped by the sequence indices 2, 1 and 3, respectively,according to the process 40. Then, the association set indices 6, 7 and11 with the sequence indices 1, 2 and 3 are used for determining theHARQ resource according to the process 40, when the advanced UE intendsto transmit the HARQ feedback in the subframe 2. In addition, thedetermination of the HARQ resource in the subframe 2 is illustrated inthe present example, those skilled in the art can readily determine theHARQ resource in other subframes according to the above description.Note that an interleaving for the first new association set (12, 6, 7,11) is performed according to the UL/DL configuration 4. That is, therule for performing the interleaving used by the legacy UE is kept thesame, e.g., the number of the sequence indices M which is the size ofthe first new association set is 4, such that the legacy UE can transmitthe HARQ feedback regularly. Thus, the collision of the HARQ resourcescan be solved, while the operation of the legacy UE is not affected. Asa result, communications between the network and the legacy UE and theadvanced UE can proceed regularly.

Please refer to FIG. 6, which is a schematic diagram of association setsof the advanced UE and the legacy UE with different UL/DL configurationsaccording to an example of the present invention, wherein subframeallocations corresponding to the UL/DL configurations are shown in theupper half of FIG. 6. In detail, the advanced UE and the legacy UE areconfigured with the UL/DL configurations 4 and 3, respectively, whereinthe UL/DL configuration of the legacy UE may be a SIB1 configuration.Association sets for various UL subframes and UL/DL configurations areshown in FIG. 6. For example, the association set of the subframe 2which includes the association set indices 12, 8, 7 and 11 will be usedfor determining HARQ resource according to the prior art, when theadvanced UE intends to transmit a HARQ feedback in the subframe 2. Inaddition, the HARQ feedback corresponds to DL receptions in DL subframescorresponding to the association set indices 12, 8, 7 and 11, whereinthe DL subframes are the subframes 0, 4, 5 and 1 of a previous frame inthe present example. The sequence indices m mapping to the associationset indices are shown on the top of the association set. For example,the association set indices 12, 8, 7 and 11 of the subframe 2 of theUL/DL configuration 4 are mapped by the sequence indices 0, 1, 2 and 3,respectively.

According to the process 40 and the above description, the advanced UEdetermines the first new association set as the association set of thelegacy UE, replaces the subset of the first new association set by thesubset of the association set of the UL subframe of the UL/DLconfiguration 4 when the legacy UE is not able to perform the receptionin the at least one subframe corresponding to the subset of the firstnew association set, determines a second new association set of the ULsubframe of the UL/DL configuration 4, and configures the mappingbetween the sequence indices and the first new association set as themapping used by the legacy UE. Preferably, each association set index ofthe subset of the UL subframe of the UL/DL configuration 4 and eachassociation set index of the rest of the first new association set(i.e., association set index not being replaced) are different. That is,when the subframe 2 is considered, the advanced UE first determines thefirst new association set as (7, 6, 11). Then, the advanced UE replacesthe association set index 6 by the association set index 12, since theassociation set index 6 corresponds to the subframe 6 in the previousframe and the subframe 6 is not available for the legacy UE. Forexample, the network does not schedule the subframe 6 to the legacy UEfor performing the reception, and the advanced UE may be notified by thenetwork such scheduling decision. Then, the advanced UE determines thesecond new association set as “8” according to the UL/DL configuration4.

As can be seen, the second new association set does not overlap with thefirst new association set. In addition, the second new association setdoes not overlap with the subset of the UL subframe of the UL/DLconfiguration 4 (i.e., “12”), as shown in FIG. 7. The association setindices 7, 12 and 11 are now mapped by the sequence indices 0, 1 and 2,respectively, according to the process 40. Preferably, a resource region(e.g., physical UL control channel (PUCCH) resource region)corresponding to the first new association set does not overlap with aresource region corresponding to the second new association set. Then,the association set indices 7, 12 and 11 in the first new associationset with the sequence indices 0, 1 and 2 and the second new associationset with corresponding sequence index are used for determining the HARQresource according to the process 40, when the advanced UE intends totransmit the HARQ feedback in the subframe 2. Accordingly, the HARQresource in the resource region corresponding to the first newassociation set do not overlap with the HARQ resource in the resourceregion corresponding to the second new association set. Note that asequence index for the association set index 8 in the second newassociation set can be specified according to system requirements anddesign considerations, and is not limited herein. In addition, thedetermination of the HARQ resource in the subframe 2 is illustrated inthe present example, those skilled in the art can readily determine theHARQ resource in other subframes according to the above description.Note that an interleaving for the first subset of the association set(7, 12, 11) is performed according to the UL/DL configuration 3. Thatis, the rule for performing the interleaving used by the legacy UE iskept the same, e.g., the number of the sequence indices M is 3, suchthat the legacy UE can transmit the HARQ feedback regularly. Thus, thecollision of the HARQ resources can be solved, while the operation ofthe legacy UE is not affected. As a result, communications between thenetwork and the legacy UE and the advanced UE can proceed regularly.

Please refer to FIG. 7, which is a schematic diagram of association setsof the advanced UE and the legacy UE with different UL/DL configurationsaccording to an example of the present invention, wherein subframeallocations corresponding to the UL/DL configurations are shown in theupper half of FIG. 7. In detail, the advanced UE and the legacy UE areconfigured with the UL/DL configurations 4 and 3, respectively, whereinthe UL/DL configuration of the legacy UE may be a SIB1 configuration.Association sets for various UL subframes and UL/DL configurations areshown in FIG. 7. Detailed description of the association sets can bereferred to the previous description, and is not narrated herein.

According to the process 40 and the above description, the advanced UEdetermines the first new association set as the association set of thelegacy UE, replaces the subset of the first new association set by thesubset of the association set of the UL subframe of the UL/DLconfiguration 4 when the legacy UE is not able to perform the receptionin the at least one subframe corresponding to the subset of the firstnew association set, determines a second new association set of the ULsubframe of the UL/DL configuration 4, and configures the mappingbetween the sequence indices and the first new association set as themapping used by the legacy UE. Preferably, each association set index ofthe subset of the UL subframe of the UL/DL configuration 4 and eachassociation set index of the rest of the first new association set(i.e., association set index not being replaced) are different. That is,when the subframe 2 is considered, the advanced UE first determines thefirst new association set as (7, 6, 11). Then, the advanced UE replacesthe association set index 6 by the association set index 12, since theassociation set index 6 corresponds to the subframe 6 in the previousframe and the subframe 6 is not available for the legacy UE. Forexample, the network does not schedule the subframe 6 to the legacy UEfor performing the reception, and the advanced UE may be notified by thenetwork such scheduling decision. Then, the advanced UE determines thesecond new association set as (8, 7, 11) according to the UL/DLconfiguration 4.

As can be seen, the second new association set overlaps with the firstnew association set. In addition, the second new association set doesnot overlap with the subset of the UL subframe of the UL/DLconfiguration 4 (i.e., “12”), as shown in FIG. 7. The association setindices 7, 12 and 11 are now mapped by the sequence indices 0, 1 and 2,respectively, according to the process 40. Preferably, a resource region(e.g., PUCCH resource region) corresponding to the first new associationset does not overlap with a resource region corresponding to the secondnew association set. Then, the association set index 12 in the first newassociation set with the sequence index 1 and the second new associationset with corresponding sequence indices are used for determining theHARQ resource according to the process 40, when the advanced UE intendsto transmit the HARQ feedback in the subframe 2. Accordingly, the HARQresource in the resource region corresponding to the first newassociation set do not overlap with the HARQ resource in the resourceregion corresponding to the second new association set. Note that thesequence indices for the association set indices 8, 7 and 11 in thesecond new association set can be specified according to systemrequirements and design considerations, and is not limited herein. Inaddition, the determination of the HARQ resource in the subframe 2 isillustrated in the present example, those skilled in the art can readilydetermine the HARQ resource in other subframes according to the abovedescription. Note that an interleaving for the first subset of theassociation set (7, 12, 11) is performed according to the UL/DLconfiguration 3. That is, the rule for performing the interleaving usedby the legacy UE is kept the same, e.g., the number of the sequenceindices M is 3, such that the legacy UE can transmit the HARQ feedbackregularly. Thus, the collision of the HARQ resources can be solved,while the operation of the legacy UE is not affected. As a result,communications between the network and the legacy UE and the advanced UEcan proceed regularly.

Please refer to FIG. 8, which is a schematic diagram of association setsof the advanced UE and the legacy UE with different UL/DL configurationsaccording to an example of the present invention, wherein subframeallocations corresponding to the UL/DL configurations are shown in theupper half of FIG. 8. In detail, the advanced UE and the legacy UE areconfigured with the UL/DL configurations 3 and 4, respectively, whereinthe UL/DL configuration of the legacy UE may be a SIB1 configuration.Association sets for various UL subframes and UL/DL configurations areshown in FIG. 8. For example, the association set of the subframe 2which includes the association set indices 7, 6 and 11 will be used fordetermining HARQ resource according to the prior art, when the advancedUE intends to transmit a HARQ feedback in the subframe 2. In addition,the HARQ feedback corresponds to DL receptions in DL subframescorresponding to the association set indices 7, 6 and 11, wherein the DLsubframes are the subframes 5, 6 and 1 of a previous frame in thepresent example. The sequence indices m mapping to the association setindices are shown on the top of the association set. For example, theassociation set indices 7, 6 and 11 of the subframe 2 of the UL/DLconfiguration 3 are mapped by the sequence indices 0, 1 and 2,respectively.

According to the process 40 and the above description, the advanced UEdetermines the first new association set as the association set of thelegacy UE, replaces the subset of the first new association set by thesubset of the association set of the UL subframe of the UL/DLconfiguration 4 when the legacy UE is not able to perform the receptionin the at least one subframe corresponding to the subset of the firstnew association set, determines a second new association set of the ULsubframe of the UL/DL configuration 4, and configures the mappingbetween the sequence indices and the first new association set as themapping used by the legacy UE. Preferably, each association set index ofthe subset of the UL subframe of the UL/DL configuration 3 and eachassociation set index of the rest of the first new association set(i.e., association set index not being replaced) are different. That is,when the subframe 2 is considered, the advanced UE first determines thefirst new association set as (12, 8, 7, 11). Then, the advanced UEreplaces the association set index 8 by the association set index 6,since the association set index 8 corresponds to the subframe 4 in theprevious frame and the subframe 4 is actually a UL subframe. Morespecifically, the subframe 4 is a DL subframe determined according tothe UL/DL configuration 4 operated by the legacy UE, and is the ULsubframe determined according to the UL/DL configuration 3 which is thereal configuration operated by the network and the advanced UE. Then,the advanced UE determines the second new association set as (7, 11)according to the UL/DL configuration 3.

As can be seen, the second new association set overlaps with the firstnew association set. In addition, the second new association set doesnot overlap with the subset of the UL subframe of the UL/DLconfiguration 3 (i.e., “6”), as shown in FIG. 8. The association setindices 12, 6, 7 and 11 are now mapped by the sequence indices 0, 1, 2and 3, respectively, according to the process 40. Preferably, a resourceregion (e.g., PUCCH resource region) corresponding to the first newassociation set does not overlap with a resource region corresponding tothe second new association set. Then, the association set index 6 in thefirst subset of the association set with the sequence index 1 and thesecond subset of the association set with corresponding sequence indicesare used for determining the HARQ resource according to the process 40,when the advanced UE intends to transmit the HARQ feedback in thesubframe 2. Accordingly, the HARQ resource in the resource regioncorresponding to the first new association set do not overlap with theHARQ resource in the resource region corresponding to the second newassociation set. Note that sequence indices for the association setindices 7 and 11 in the second new association set can be specifiedaccording to system requirements and design considerations, and is notlimited herein. In addition, the determination of the HARQ resource inthe subframe 2 is illustrated in the present example, those skilled inthe art can readily determine the HARQ resource in other subframesaccording to the above description. Note that an interleaving for thefirst subset of the association set (12, 6, 7, 11) is performedaccording to the UL/DL configuration 4. That is, the rule for performingthe interleaving used by the legacy UE is kept the same, e.g., thenumber of the sequence indices M is 4, such that the legacy UE cantransmit the HARQ feedback regularly. Thus, the collision of the HARQresources can be solved, while the operation of the legacy UE is notaffected. As a result, communications between the network and the legacyUE and the advanced UE can proceed regularly.

Please refer to FIG. 9, which is a schematic diagram of association setsof the advanced UE and the legacy UE with different UL/DL configurationsaccording to an example of the present invention. In detail, theadvanced UE and the legacy UE are configured with the UL/DLconfigurations 0 and 2, respectively, wherein the UL/DL configuration ofthe legacy UE may be a SIB1 configuration. Association sets for variousUL subframes and UL/DL configurations are shown in FIG. 9. Detaileddescription of the association sets can be referred to the previousdescription, and is not narrated herein. Note that the legacy UE isrestricted to perform receptions in the subframes 0 and 5 of the frames.For example, the network only schedules the legacy UE to perform thereceptions in the subframes 0 and 5 of the frames, and the advanced UEmay be notified by the network such scheduling decision.

According to the process 40 and the above description, the advanced UEdetermines the first new association set as the association set of thelegacy UE, replaces the subset of the first new association set by thesubset of the association set of the UL subframe of the UL/DLconfiguration 0 when the legacy UE is not able to perform the receptionin the at least one subframe corresponding to the subset of the firstnew association set, and configures the mapping between the sequenceindices and the first new association set as the mapping used by thelegacy UE. Preferably, each association set index of the subset of theUL subframe of the UL/DL configuration 0 and each association set indexof the rest of the first new association set (i.e., association setindex not being replaced) are different. That is, when the subframe 2 isconsidered, the advanced UE first determines the first new associationset as (8, 7, 4, 6). Then, the advanced UE replaces the association setindices 8, 4 and 6 by the association set index 6, since the associationset indices 8, 4 and 6 correspond to the subframes 4, 8 and 6 where noreception is performed. The association set indices of the first newassociation set which are 6 and 7 are mapped by the sequence indices 0and 1, respectively, according to the process 40. Then, the associationset index 6 in the first new association set with the sequence index 0is used for determining the HARQ resource according to the process 40,when the advanced UE intends to transmit the HARQ feedback in thesubframe 2. In addition, the determination of the HARQ resource in thesubframe 2 is illustrated in the present example, those skilled in theart can readily determine the HARQ resource in other subframes accordingto the above description. Note that an interleaving for the first newassociation set (6, 7) is performed according to the UL/DL configuration2. That is, the rule for performing the interleaving used by the legacyUE is kept the same, e.g., the number of the sequence indices M which isthe size of the first new association set is 4, such that the legacy UEcan transmit the HARQ feedback regularly. Thus, the collision of theHARQ resources can be solved, while the operation of the legacy UE isnot affected. As a result, communications between the network and thelegacy UE and the advanced UE can proceed regularly.

Please refer to FIG. 10, which is a schematic diagram of associationsets of the advanced UE and the legacy UE with different UL/DLconfigurations according to an example of the present invention, whereinsubframe allocations corresponding to the UL/DL configurations are shownin the upper half of FIG. 10. In detail, the advanced UE and the legacyUE are configured with the UL/DL configurations 1 and 3, respectively,wherein the UL/DL configuration of the legacy UE may be a SIB1configuration. Association sets for various UL subframes and UL/DLconfigurations are shown in FIG. 10. For example, the association set ofthe subframe 3 which includes the association set index 4 will be usedfor determining HARQ resource according to the prior art, when theadvanced UE intends to transmit a HARQ feedback in the subframe 3. Notethat the HARQ feedback corresponds to a DL reception in a DL subframecorresponding to the association set index 4, wherein the DL subframe isthe subframe 9 of a previous frame in the present example. The sequenceindices m mapping to the association set indices are shown on the top ofthe association set. For example, the association set index 4 of thesubframe 3 of the UL/DL configuration 1 is mapped by the sequence index0.

According to the process 40 and the above description, the advanced UEcan determine the first new association set as the association set ofthe legacy UE, replace the subset of the first new association set bythe subset of the association set of the UL subframe of the UL/DLconfiguration 1, when the legacy UE is not able to perform the receptionin the at least one subframe corresponding to the subset of the firstnew association set, and configure the mapping between the sequenceindices and the first new association set as the mapping used by thelegacy UE. Preferably, each association set index of the subset of theUL subframe of the UL/DL configuration 1 and each association set indexof the rest of the first new association set (i.e., association setindex not being replaced) are different. That is, when the subframe 3 isconsidered, the advanced UE first determines the first new associationset as (6, 5). Then, the advanced UE replaces the association setindices 6 and 5 by the association set index 4, since the associationset indices 6 and 5 correspond to the subframes 7 and 8 in the previousframe and the subframes 7 and 8 are actually UL subframes. Morespecifically, the subframes 7 and 8 are DL subframes determinedaccording to the UL/DL configuration 3 operated by the legacy UE, andare the UL subframes determined according to the UL/DL configuration 1which is the real configuration operated by the network and the advancedUE. Then, the association set index 4 with a sequence index (e.g., 0) isused for determining the HARQ resource according to the process 40, whenthe advanced UE intends to transmit the HARQ feedback in the subframe 3.Note that the advanced UE can actually stop configuring the mapping anddetermine the HARQ resource according to the first new association setwithout using the mapping, when the advanced UE replaces the first newassociation set completely by the subset of the association set of theUL subframe of the second UL/DL configuration which is true in thepresent example. The reason is that the advanced UE does not need totake the operation of the legacy UE into consideration, when theassociation indices which may be used by the legacy UE are completelyreplaced. In addition, the determination of the HARQ resource in thesubframe 3 is illustrated in the present example, those skilled in theart can readily determine the HARQ resource in other subframes accordingto the above description. Thus, the collision of the HARQ resources canbe solved, while the operation of the legacy UE is not affected. As aresult, communications between the network and the legacy UE and theadvanced UE can proceed regularly.

The process 40 and the above description can be applied to the case ofcarrier aggregation (CA), when 2 UL/DL configurations which correspondto 2 component carriers configured to the advanced UE, respectively, areconsidered. In detail, the first UL/DL configuration may correspond to aprimary cell (e.g., primary component carrier), and the second UL/DLconfiguration may correspond to a secondary cell (e.g., secondarycomponent carrier). Similar to the operation of the legacy UE, theoperation related to the primary cell should not be affected, since mostcontrol information is transmitted via the primary cell. Thus, theprocess 40 and the above description can be readily applied (i.e.,extended) to the case of the CA, after replacing the legacy UE by theprimary cell (i.e., the first UL/DL configuration of the primary cell)and replacing the advanced UE by the secondary cell (i.e., the secondUL/DL configuration of the secondary cell) in the abovementioneddescription and examples.

Those skilled in the art should readily make combinations, modificationsand/or alterations on the abovementioned description and examples. Theabovementioned steps of the processes including suggested steps can berealized by means that could be a hardware, a firmware known as acombination of a hardware device and computer instructions and data thatreside as read-only software on the hardware device, or an electronicsystem. Examples of hardware can include analog, digital and mixedcircuits known as microcircuit, microchip, or silicon chip. Examples ofthe electronic system can include a system on chip (SOC), system inpackage (SiP), a computer on module (COM), and the communication device30.

To sum up, the present invention provides a method for handling HARQResource in the TDD mode. Since the collision of the HARQ resourcesoccurred due to different UL/DL configurations of the advanced UE andthe legacy UE is solved, while the operation of the legacy UE is notaffected. As a result, communications between the network and the legacyUE and the advanced UE can proceed regularly.

Those skilled in the art will readily observe that numerousmodifications and alterations of the device and method may be made whileretaining the teachings of the invention. Accordingly, the abovedisclosure should be construed as limited only by the metes and boundsof the appended claims.

What is claimed is:
 1. A method of determining hybrid automatic repeatrequest (HARQ) resource of an uplink (UL) subframe for an advancedcommunication device, the method comprising: determining a first newassociation set of the UL subframe according to an association set ofthe UL subframe of a first UL/downlink (DL) configuration of a legacycommunication device; replacing a subset of the first new associationset by a subset of an association set of the UL subframe of a secondUL/DL configuration of the advanced communication device, when thelegacy communication device is not able to perform a reception in atleast one subframe corresponding to the subset of the first newassociation set; configuring a mapping between at least one sequenceindex of the UL subframe of the first UL/DL configuration and the firstnew association set according to the first UL/DL configuration; anddetermining the HARQ resource of the UL subframe according to themapping and the first new association set; wherein the first UL/DLconfiguration is a System Information Block Type 1 (SIB 1)configuration.
 2. The method of claim 1, wherein the legacycommunication device is not able to perform the reception in the atleast one subframe, if the at least one subframe is at least one DLsubframe according to the first UL/DL configuration and is at least oneUL subframe according to the second UL/DL configuration.
 3. The methodof claim 1, wherein the legacy communication device is not able toperform the reception in the at least one subframe, if a networknotifies the advanced communication device that the network does notschedule the at least one subframe to the legacy communication devicefor performing the reception.
 4. The method of claim 1, wherein eachassociation set index of the subset of the UL subframe of the secondUL/DL configuration and each association set index of the rest of thefirst new association set are different.
 5. The method of claim 1,further comprising: determining a second new association set accordingto the association set of the UL subframe of the second UL/DLconfiguration; and determining the HARQ resource of the UL subframeaccording to the mapping, the first new association set and the secondnew association set.
 6. The method of claim 5, wherein the second newassociation set does not overlap with the subset of the UL subframe ofthe second UL/DL configuration.
 7. The method of claim 5, wherein thesecond new association set partly overlaps with the first newassociation set.
 8. The method of claim 5, wherein the second newassociation set does not overlap with the first new association set. 9.The method of claim 5, wherein a resource region corresponding to thefirst new association set does not overlap with a resource regioncorresponding to the second new association set.
 10. The method of claim1, wherein when the advanced UE replaces the first new association setcompletely by the subset of the association set of the UL subframe ofthe second UL/DL configuration, the advanced UE stops configuring themapping and determines the HARQ resource of the UL subframe according tothe first new association set without using the mapping.
 11. The methodof claim 1, wherein an interleaving for the first new association set isperformed according to the first UL/DL configuration.
 12. The method ofclaim 1, wherein the step of determining the first new association setof the UL subframe according to the association set of the UL subframeof the first UL/DL configuration comprises: determining the first newassociation set as the association set of the UL subframe of the firstUL/DL configuration.
 13. The method of claim 1, wherein the step ofconfiguring the mapping between the at least one sequence index of theUL subframe of the first UL/DL configuration and the first newassociation set according to the first UL/DL configuration comprises:configuring the mapping as a mapping between the at least one sequenceindex of the UL subframe of the first UL/DL configuration and theassociation set of the UL subframe of the first UL/DL configuration. 14.The method of claim 1, wherein the legacy communication device and theadvanced communication device are the same communication device, thefirst UL/DL configuration corresponds to a first component carrier, andthe second UL/DL configuration corresponds to a second componentcarrier.